That is interesting, I imported a 97 M3 last summer (July 2015) and I did not have an ITN.

My wife and I drove down to get the car and I drove it home on Connecticut plates. On the way there the US border guard counted my cash, looked at a copy of my RIV exemption paperwork and let me go. On the way home I declared the car at the Canadian border, had the car inspected, completed the RIV paperwork, paid duty and drove home. Aside from 13 hours of driving it was an easy process.